A glass laminate provides superior safety because even when it is broken by, for example, an external impact, glass fragments thereof are hardly scattered, and is therefore widely used as a window pane for automobiles, rail cars, aircraft, boats and ships, and buildings.
Examples of such a glass laminate include those obtained by interposing an interlayer film for glass laminate between at least a pair of glass sheets and integrating them into one unit. As such an interlayer film for glass laminate, a plasticized polyvinyl acetal resin film, an ethylene-vinyl acetate copolymer resin film, an ethylene-acrylic acid copolymer resin film, a polyurethane resin film, a sulfur-containing polyurethane resin film, a polyvinyl alcohol resin film, or the like is usually used.
For example, Japanese Patent Application Laid-open No. S60-60149 (hereinafter, simply referred to as “Patent Document 1”) discloses, as an interlayer film for glass laminate, a polyvinyl butyral sheet plasticized with a multiester of an alcohol having 2 to 4 hydroxyl groups and a C16 to C20 unsaturated fatty acid having a hydroxyl group attached to the acid molecule. The polyvinyl butyral sheet disclosed in Patent Document 1 further contains, in addition to the multiester component, a monoester of a glycol and a C16 to C20 unsaturated fatty acid having a hydroxyl group attached to the acid molecule. It is to be noted that Patent Document 1 describes that the amount of such plasticizer blend contained in the laminate interlayer film should be in the range of 10 to 55 parts per hundred parts of PVB resin (phr).
Patent Document 1 further describes that a glass laminate using the plasticized polyvinyl butyral sheet has improved peel adhesion and penetration resistance over a wide range of temperatures.
On the other hand, WO 01/19747 (hereinafter, simply referred to as “Patent Document 2”) discloses an interlayer film containing 50 to 80 wt % of PVB (acetalized polyvinyl alcohol) and 20 to 50 wt % of a softener. Further, 30 to 70 wt % of the softener contained in the interlayer film disclosed in Patent Document 2 is composed of one or more polyalkylene glycols represented by the following formulas (A1) to (A6) or derivatives thereof.HO—(R—O)n—H  (A1)
where R is an alkylene group and n>5HO—(CH2—CH2—O)n—(CH2—CH(CH3)—O)m—H  (A2)
where n>2, m>3, and (n+m)<25R1O—(CH2—CH2—O)n—(CH2—CH(CH3)—O)m—H  (A3) orHO—(CH2—CH2—O)n—(CH2—CH(CH3)O)m—R1  (A4)
where n>2, m>3, (n+m)<25, and R1 is an organic groupR1—O—(R2—O)n—H  (A5)
where R2 is an alkylene group, n>2, and R1 is an organic groupR1—O—(R2—O)n—R3  (A6)
where R2 is an alkylene group, n>5, and R1 and R3 are each an organic group
Patent Document 2 describes that the interlayer film contains, as a part of the softener, one or more of the above-described specific compounds in the above-described specific ratio, and therefore a glass laminate using such an interlayer film has improved sound insulation.    [Patent Document 1] Japanese Patent Laying-Open No. 1985-60149    [Patent Document 2] WO 01/19747 A1